The present invention relates to a reaction product of a titanium ester and 2,4-pentanedione which has been modified so as to lower its freezing point.
It has long been known that titanium esters react with high molecular weight hydroxyl-containing compounds so as to cross-link them and produce gels; J. Oil and Colour Chem Assoc. 31, 405 (1948). However, the cross-linking reaction made through the use of simple alkyl esters of titanium proceeds too rapidly for most industrial uses. The cross-linking rate imparted by titanium esters can be depressed by combining a titanium ester with a variety of multifunctional compounds including 2,4-pentanedione (also known as acetylacetone); U.S. Pat. No. 2,680,108. It should be noted that there is disagreement as to the structure of the complexes or chelates so-formed; cf. the structure given in the patent with that given by Yamamoto et al., J.A.C.S. 79 (1957), 4344-8.
The reaction product of tetraisopropyl titanate (also known as tetraisopropoxytitanium) and 2,4-pentanedione, at a titanate:pentanedione mol ratio of 1:2, finds several industrial uses. Among others, that reaction product is used to cross-link high molecular weight compounds (e.g., hydroxypropyl guar gum), and the cross-linked high molecular material is used to fracture oil-bearing formations. That reaction product is normally a liquid, and sometimes it remains in the liquid state even after having been supercooled to some considerable extent. However, in the supercooled state, it sometimes spontaneously freezes, especially in the presence of a nucleating agent, such as dust or a part of the reaction product in crystal form. The reaction product of tetraisopropyl titanate and 2,4-pentanedione at a 1:1 mol ratio has an even greater tendency to freeze.
In U.S. Pat. No. 4,313,851, it is proposed that the addition of a small amount of water will inhibit crystallization of the reaction product of one mol of tetraisopropyl titanate with two mols of 2,4-pentanedione. The technique used in that patent results in hydrolysis of that reaction product, liberating isopropyl alcohol. In any event, that technique did not prevent freezing in the presence of a nucleating agent.